The present invention pertains to a device for transporting printed products such as book blocks, books or stacks of printed matter, particularly folded and/or unfolded sheets, with a conveying system having several driven endless conveyors arranged in parallel.
A device of this type is known from patent DD 105 173. On a section of a roller conveyor, transport elements that can be driven transverse to transport rollers driven in the transport direction, e.g., transport chains that revolve transverse to the transport direction, can be raised above the upper plane of the transport rollers and lowered below this plane between the transport rollers that are driven in the conveying direction. This device makes it possible to transfer objects transported on a continuous roller conveyor to roller conveyors arranged perpendicular thereto or to transfer objects to the continuous roller conveyor from roller conveyors arranged perpendicular thereto in certain regions of the roller conveyor.
de 28 43 599 A1 describes a transport device for book blocks or books, in which driven rollers are arranged between revolving belts of a pivoted belt system such that their axes approximately extend along the transport direction of the belts and the transport plane of the rollers that are rigidly supported in the frame lies underneath the transport plane of the belt in the upper pivoting position of the belt system and above the transport plane of the belts in the lower pivoting position of the belt system. The belt system is realized in the form of a conveying section in a transport path composed of conveyor belts. The rollers can transfer a printed product to a conveyor belt arranged perpendicular to the transport path by pivoting the belt system downward. The conveying device could conceivably also operate in reverse in the sense of an inward transfer.
Various outward transfer principles are systematically illustrated in VDI Guideline 2340.
One disadvantage of the aforementioned devices can be seen in that a gentle inward and outward transfer or cross-conveying, especially of sensitive individual products such as book blocks, books or stacks of printed matter, particularly consisting of folded and/or unfolded sheets, or of similar printed products cannot be ensured. The printed products are subjected to abrupt changes in the transport direction and acceleration processes that inevitably cause slippage when they are lifted off or deposited onto continuous conveyors such that marking of the surfaces or deformation or even the destruction of the printed products or stacks can occur.
EP 1 380 523 A1 discloses a transfer device for individual products to be transported, in which a conveying means that transports toward the transfer device is lifted off the transport plane and decelerated by means of braking rails that can be raised and lowered. The slightly lowered braking rails subsequently transfer the product to be transported to the roller conveyor that is simultaneously raised above the transport plane in order to laterally transport away the product. The lifting movements of the braking rails and of the roller conveyor are respectively realized with parallelogram lifting mechanisms and motion-coupled in that the oscillating levers arranged on identical pivoting axes are fixed at a defined angle relative to one another. In the lower starting position, the oscillating levers of the parallelogram lifting mechanism of the roller conveyor are approximately oriented parallel to the transport plane while the oscillating levers of the parallelogram lifting mechanism of the braking rails are oriented directly in front of their vertical zenith position. The common pivoting of the aforementioned oscillating levers causes the roller conveyor to carry out a vertical movement with a comparatively small horizontal component while the braking rails are initially raised above their zenith position and then minimally lowered. The horizontal movement of the braking rails is used for pushing a product to be transported which is decelerated on the braking rails against a stopping element and thusly aligning said product.
This transfer device is suitable for the outward transfer as well as the inward transfer of products to be transported. During an outward transfer, the raised product to be transported is decelerated by the braking rails. During an inward transfer, the product is pre-accelerated in the subsequent transport direction due to the horizontal movement of the braking rails that takes place simultaneously with the lowering movement. However, the complicated construction with two parallelogram lifting mechanisms is considered disadvantageous in this transfer device. Due to the motion coupling and the initial upward motion of the braking rails during their return movement, the lowering of the braking rails cannot take place until the product to be transported is transported away from the transfer point in its entirety because it would otherwise be decelerated once again by the braking rails. This results in capacity limitations.